The present invention relates generally to monitoring the proximity of persons or objects, and more particularly to a communication system for use in monitoring the proximity of persons or objects.
The recent explosion of wireless communication devices and applications lends itself to many uses besides basic communications. The predominant use of such devices has been to allow family and friends to keep in touch with each other. However, due to high monthly fees it has been uneconomical to provide such devices to small children. In addition, very small children would not be able to properly operate the typical cellular phone. However, it is of paramount concern to monitor children for their safety. Therefore, the solution has arisen to use wireless technology to satisfy the need to provide child location systems.
One prior art solution is to use the Global Positioning System to provide location services. Although effective, the cost of the technology is prohibitive, and there is little call to locate a person or object anywhere on the globe. This is also true in the case of child location. Another prior art solution has been to install radio frequency (RF) tags, such as in a car for example, which can transmit a location of the car if it is stolen. Again the technology is expensive and requires a large transmitter power source, such as a car battery. In addition, special receivers and software are needed to detect the signal. Another prior art solution uses cellular technology to locate a control signal scan of a cellular device. However, this technique requires on-board emergency activation circuitry and a high power source for the continuous multicell control signal scan and response transmissions thereto. All of the above suffer from high expense, being impractical, or being difficulty to use.
Other prior art solution attempt to provide a relatively lower cost solution. One such solution provides similar communication devices between a guardian and a child operable on a cellular network. However, such devices require complicated addressing and timing schemes to avoid interference with similar local devices. Other solutions provide a transmitter beacon on a child, which is simple, and a directional receiver with a location display for the parent. However, the directional receiver requires special hardware and constant monitoring of the parent. This simplistic method is little better than the parent keeping a constant eye on the child, which is still the method used most frequently today. Still another solution provides a customized system that provides a bracelet transceiver for the child and a monitor transceiver for a parent, wherein the parent can signal the bracelet to let the child know to return to the parent. However, this system is not autonomous and requires a positive action on the part of the parent to provide a system activation signal.
Accordingly, there is a need for an improved monitoring communication system that autonomously monitors proximity of a person or object. In particular, it would be of benefit to be able to define the proximal boundaries of the system, and to automatically alert if the boundary is violated. It would also be advantageous if current low-cost technology could be used without the requirement for customized hardware. A further benefit would allow the automatic hand-off or transfer of monitoring capabilities between communication devices.
The present invention is directed to a method and system of proximity monitoring in a wireless communication system operable on at least two wireless local area networks. The invention is operable using at least two master communication devices supporting respective wireless local area networks, and at least one wireless monitor device as a slave unit operable in either of the wireless local area networks. The master and slave devices transceiver signals on the respective wireless local area network of the master device. The transceived signals are used for proximity monitoring of the salve device by the master device.
One aspect of the present invention is the triggering of an alarm in a master device when the slave device is no longer in proximity thereto. This is applicable to one or more master devices that are able to monitor the slave device on its respective local area network. In particular, master devices can transfer proximity monitoring responsibilities of the slave device between themselves. Transferring includes a wide area network communication between the master units indicating a transfer is to take place. A time-out period is provided for the slave device to transfer between the local area network of the master devices. If the time-out period expires before the transferring is complete, an alarm is sounded. An acknowledgement is provided between the master devices to confirm the transferral.
Another aspect of the present invention is the measuring the signal strength threshold of a slave device to defined a proximity boundary for the device in the local area network.
Another aspect of the present invention is the measuring the signal strength threshold of a slave device to defined a proximity boundary for the device in the local area network, which is assigned to all the slave devices in the local area network to define a group threshold.
Another aspect of the present invention is slaving the slave device to the master device providing the strongest received signal from a master device.
Another aspect of the present invention is the querying of other master devices to locate a slave device that is no longer in proximity.